Between 1832 and 1849 New York City grew more densely populated. Immigration, particularly from famine-stricken Ireland, had exploded, and the downtown wards were extraordinarily overcrowded. Tenements, which were constructed for the purpose of housing the exploding population, generally measured twenty-five feet wide by seventy-feet deep and contained twenty-four apartments. Each building sheltered at least one family per apartment, but most housed more. Those who could not secure this comparatively desirable, low-cost housing were forced into converted, single-family frame dwellings and boardinghouses. All of this added up to a staggering population density – estimates suggest that the total German population alone would have been enough to form the fourth largest city in the United States by 1855. The Common Council added three more wards below 20th Street in an attempt to ease governance of the city, but this political expansion did little to change the situation on the ground for most working New Yorkers. The streets, already filthy in 1832, were buried under even more layers of dirt, manure and refuse seventeen years later. Troubling aspects of the modern city already visible in 1832 — chaotic commerce, increasingly visible poverty and vice, a shortage of fresh, potable water, slapdash firefighting capabilities, and sharper disparities between the wealthy and the poor — had become more severe. (For more on New York’s water supply and on the upheavals caused by fire in the nineteenth century, click on the links below.)

Cholera again ravaged Europe in 1848. In December the New York, a ship with three hundred passengers that had been exposed to cholera, was quarantined on Staten Island. Some of the passengers escaped to Manhattan, where cholera cases began to appear before the new year. The freezing winter of 1848-1849 limited the spread of cholera, and few cases were reported during the first months of 1849. But by mid-May, increasing numbers of cholera cases were appearing, and by June the outbreak had reached epidemic proportions.